Earlier this year, we covered the 3Doodler, a pen that lets users sketch 3D objects with plastic filament, almost like a 3D printer. It's a fun little gadget, but what if someone made a device that offers similar freedom, except it built objects over 10 times larger? It might look something like the Mataerial 3D printer, which uses a robotic arm and quick-solidifying material to form rigid, free-flowing structures on almost any surface, even vertical ones.